DNA Vaccines Show Promise in Preventing Dental Caries

In a report on a preclinical investigation titled "Flagellin Enhances Saliva Ig A Response and Protection of Anti-caries DNA Vaccine," lead author Wei Shi, Wuhan Institute of Virology, Chinese Academy of Sciences, and his team of researchers demonstrate that anti-caries DNA vaccines, including pGJA-P/VAX, are promising for preventing dental caries. However, challenges remain because of the low immunogenicity of DNA vaccines.

This study is published in the Journal of Dental Research, the official publication of the International and American Associations for Dental Research (IADR/AADR).

In this study, Shi and team used recombinant flagellin protein derived from Salmonella as mucosal adjuvant for anti-caries DNA vaccine (pGJA-P/VAX) and analyzed the effects of Salmonella protein on the serum surface protein immunoglobulin G and saliva surface protein immunoglobulin A antibody responses, the colonization of Streptococcus mutans (S. mutans) on rodent teeth, and the formation of caries lesions. The results showed that Salmonella promoted the production of surface protein immunoglobulin G in serum and secretory immunoglobulin A in saliva of animals by intranasal immunization with pGJA-P/VAX plus Salmonella.

Furthermore, Shi found that enhanced surface protein immunoglobulin A responses in saliva were associated with inhibition of S. mutans colonization of tooth surfaces and endowed better protection with significant less carious lesions. In conclusion, the study demonstrates that recombinant Salmonella could enhance specific immunoglobulin A responses in saliva and protective ability of pGJA-P/VAX, providing an effective mucosal adjuvant candidate for intranasal immunization of an anti-caries DNA vaccine.

Daniel Smith, The Forsyth Institute, wrote a corresponding perspective article in response to the Shi et al report titled "Prospects in Caries Vaccine Development." In it, he states that DNA vaccine approaches for dental caries have had a history of success in animal models. Dental caries vaccines, directed to key components of S. mutans colonization and enhanced by safe and effective adjuvants and optimal delivery vehicles, are likely to be forthcoming.

"These papers highlight the exciting potential of using vaccines to protect against dental caries," said JDR Editor-in-Chief William Giannobile. "This research is promising and provides optimism to help promote public health of caries-susceptible individuals."

Effect of Thyrotoxicosis on bone : A Review Article

BY : DR. GAURAV ARORA

Introduction:
Thyrotoxicosis, a clinical syndrome characterized by manifestation of excess thyroid hormone, is one of the commonly-recognised conditions of the thyroid gland. It is a hypermetabolic condition associated with elevated levels of thyroxine (T4) and/or triiodothyronine (T3).

Thyrotoxicosis causes acceleration of bone remodelling and one of the known risk factors for osteoporosis. Studies have shown that thyroid hormones have effects on bone, both in vitro and in vivo. Treatment of thyrotoxicosis leads to reversal of bone loss and metabolic alterations, and decreases the fracture risk.

Clinical presentation of thyrotoxicosis :
Thyrotoxicosis leads to an apparent increase in sympathetic nervous system symptoms.

Younger patients exhibit symptoms of more sympathetic activation, such as anxiety, hyperactivity, palpitations, sweating and tremor, while older patients have more cardiovascular symptoms, including dyspnoea, atrial fibrillation and unexplained weight loss.

One of the first reports of hyperthyroid bone disease was found in 1891 when von Recklinghausen described the "worm eaten" appearance of the long bones of a young woman who died from hyperthyroidism.

Mechanism:
Thyroid hormone directly stimulates bone resorption. This action may be mediated by a nuclear triiodothyronine (T3) receptor which has been found in rat and human osteoblast cell lines and in osteoclasts derived from an osteoclastoma . Thus, thyroid hormone may affect bone calcium metabolism either by a direct action on osteoclasts, or by acting on osteoblasts which in turn mediate osteoclastic bone resorption . Experimental studies in mice lacking either the thyroid receptor- α or -β, suggest that bone loss is mediated by thyroid receptor. Thyroid stimulating hormone (TSH) may also have a direct effect on bone formation and bone resorption, mediated via the TSH receptor on osteoblast and osteoclast precursors. However, bone loss appeared independent of TSH levels in the experiments with mice lacking specific TR isoforms.

Increased serum interleukin-6 (IL-6) concentrations in hyperthyroid patients may also play a role in thyroid hormone-stimulated bone loss. Interleukin-6 stimulates osteoclast production and may be an effector of the action of parathyroid hormone (PTH) on bone.

Biochemical markers: Biochemical markers of bone and mineral metabolism are also affected. The serum concentrations of alkaline phosphatase, osteocalcin, and osteoprotegerin , and fibroblast growth factor-23 (FGF-23) are increased in hyperthyroidism and may remain high for months after treatment, presumably due to a persistent increase in osteoblastic activity . Urinary excretion of bone collagen-derived pyridinium cross-links is increased, and falls to normal shortly after treatment

Prevention and Treatment of Reduced Bone Density:
With the introduction of antithyroid drugs and radioiodine in the 1940s, clinically apparent hyperthyroid bone disease became less common. However, bone density measurements during the last decade have demonstrated that bone loss is common in patients with overt hyperthyroidism and to a lesser extent in those with subclinical hyperthyroidism, whether caused by nodular goitre or excessive doses of thyroid hormone.

There are several measures that may prevent loss of bone density, such as titration of suppressive therapy to maintain a slightly low serum TSH concentration (e.g. between 0.1-0.5 mU/l), calcium supplementation, estrogen replacement therapy while keeping an eye on the adverse effect, and inhibitors of bone resorption (bisphosphonates or calcitonin). Guo et al, demonstrated the benefit of titrating T4 dose in patients on replacement/ suppressive dose of T4. Both lumbar and femoral bone density increased, and serum osteocalcin and urinary excretion of bone collagen-derived pyridinium cross-links decreased when the T4 dose was reduced in post-menopausal women whose initial serum TSH concentration was low.

Adequate dietary calcium intake is essential to ameliorate the adverse effects of thyroid hormone on bone. In a study of 46 post-menopausal women taking suppressive doses of T4, those taking placebo had 5 to 8 per cent reductions in bone density over a two-year period, while those given 1000 mg of calcium daily had no measurable bone loss

Conclusion
Loss of bone density and elevation of markers of bone resorption is common in thyrotoxicosis. After control of thyrotoxicosis partial recovery takes place. Treatment with anti-resorptive agents results in a better recovery. Similar phenomenon is seen during replacement therapy of patients with overt and subclinical hypothyroidism. Even euthyroid with inhibitors of bone resorption may be useful in patients with continuing bone loss. In short-term studies pamidronate reduced thyroid hormone-mediated increase in measures of bone turnover. Calcitonin reduced urinary hydroxyproline excretion and serum calcium in patients with overt patients with lower TSH values has been shown to have a lower bone density than those with high normal TSH.




References:




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Newly Identified Oral Bacterium Linked to Heart Disease and Meningitis

A novel bacterium, thought to be a common inhabitant of the oral cavity, has the potential to cause serious disease if it enters the bloodstream, according to a study in theInternational Journal of Systematic and Evolutionary Microbiology. Its identification will allow scientists to work out how it causes disease and evaluate the risk that it poses.

The similarity of S. tigurinus to other related bacteria has meant that it has existed up until now without being identified. Its recent identification is clinically important, explained Dr Andrea Zbinden who led the study. "Accurate identification of this bacterium is essential to be able to track its spread. Further research must now be done to understand the strategies S. tigurinus uses to successfully cause disease. This will allow infected patients to be treated quickly and with the right drug."The bacterium was identified by researchers at the Institute of Medical Microbiology of the University of Zurich and has been named Streptococcus tigurinus after the region of Zurich where it was first recognised. S. tigurinus was isolated from blood of patients suffering from endocarditis, meningitis and spondylodiscitis (inflammation of the spine). It bears a close resemblance to other Streptococcus strains that colonise the mouth. Bleeding gums represent a possible route of entry for oral bacteria into the bloodstream.

Dr Zbinden said that while the discovery of the bacterium is no cause for alarm, it is important that it is recognised and the risk is quantified. "This bacterium seems to have a natural potential to cause severe disease and so it's important that clinicians and microbiologists are aware of it," she said. "The next step is to work out exactly how common this bacterium is in the oral cavity and what risk it poses. Immunosuppression, abnormal heart valves, dental surgeries or chronic diseases are common predisposing factors for blood infections by this group of bacteria. However, the specific risk factors for S. tigurinus remain to be determined."

Dental Fillings That Kill Bacteria and Re-Mineralize the Tooth

Scientists using nanotechology at the University of Maryland School of Dentistry have created the first cavity-filling composite that kills harmful bacteria and regenerates tooth structure lost to bacterial decay.


Rather than just limiting decay with conventional fillings, the new composite is a revolutionary dental weapon to control harmful bacteria, which co-exist in the natural colony of microorganisms in the mouth, says professor Huakun (Hockin) Xu, PhD, MS.

"Tooth decay means that the mineral content in the tooth has been dissolved by the organic acids secreted by bacteria residing in biofilms or plaques on the tooth surface. These organisms convert carbohydrates to acids that decrease the minerals in the tooth structure," says Xu, director of the Division of Biomaterials and Tissue Engineering in the School's Department of Endodontics, Prosthodontics and Operative Dentistry.

After a dentist drills out a decayed tooth, the cavity still contains residual bacteria. Xu says it is not possible for a dentist to remove all the damaged tissue, so it's important to neutralize the harmful effects of the bacteria, which is just what the new nanocomposites are able to do.

The researchers also have built antibacterial agents into primer used first by dentists to prepare a drilled-out cavity and into adhesives that dentists spread into the cavity to make a filling stick tight to the tissue of the tooth. "The reason we want to get the antibacterial agents also into primers and adhesives is that these are the first things that cover the internal surfaces of the tooth cavity and flow into tiny dental tubules inside the tooth," says Xu. The main reason for failures in tooth restorations, says Xu, is secondary caries or decay at the restoration margins. Applying the new primer and adhesive will kill the residual bacteria, he says.

Fillings made from the School of Dentistry's new nanocomposite, with antibacterial primer and antibacterial adhesive, should last longer than the typical five to 10 years, though the scientists have not thoroughly tested longevity. Xu says a key component of the new nanocomposite and nano-structured adhesive is calcium phosphate nanoparticles that regenerate tooth minerals. The antibacterial component has a base of quaternary ammonium and silver nanoparticles along with a high pH. The alkaline pH limits acid production by tooth bacteria.

"The bottom line is we are continuing to improve these materials and making them stronger in their antibacterial and remineralizing capacities as well as increasing their longevity," Xu says.

The new products have been laboratory tested using biofilms from saliva of volunteers. The Xu team is planning to next test its products in animal teeth and in human volunteers in collaboration with the Federal University of Ceara in Brazil.

The University of Maryland has patents pending on the nanocomposite and the primer and adhesive technologies, according to Nancy Cowger, PhD, licensing officer with the University's Office of Technology Transfer (OTT).

Oral Cancer Detection Could Dramatically Increase With Saliva Test

A Michigan State University surgeon is teaming up with a Lansing-area dental benefits firm on a clinical trial to create a simple, cost-effective saliva test to detect oral cancer, a breakthrough that would drastically improve screening and result in fewer people dying of the world's sixth most common cancer.

Barry Wenig, a professor in the College of Human Medicine's Department of Surgery and lead investigator on the project, is working with Delta Dental of Michigan's Research and Data Institute to compile study data and recruit dentists. The study will enroll 100-120 patients with white lesions or growths in their mouths and tonsil areas to test as part of the clinical trial.

Wenig and his team will be looking for certain biomarkers previously identified by researchers at UCLA; the biomarkers have been shown in studies to confirm the presence of oral cancer. By creating a simple saliva test which could identify the biomarker's presence, physicians and dentists would know which patients need treatment and which ones could avoid needless and invasive biopsies.

"Most white lesions are benign, so a majority of people who develop them are getting biopsies that are not needed," Wenig said. "Conversely, a simple test would allow us to identify those patients with malignant lesions and get them into treatment quicker."

Oral cancer has a poor survival rate linked to late detection, Wenig said: Only 60 percent of patients live beyond five years after diagnosis. Among black males, the survival rate is less than 38 percent.

"The key challenge to reduce the mortality and morbidity of oral cancer is to develop strategies to identify and detect the disease when it is at a very early stage," he said.

In addition to Delta Dental's Research and Data Institute, which works with researchers from leading universities to monitor advances in science, Wenig is collaborating with PeriRx, a Pennsylvania company that will sponsor upcoming trials with the Food and Drug Administration.

"The results of this trial could be life changing for many people," said Jed Jacobson, chief science officer at Delta Dental and a licensed dentist. "It is a tremendous opportunity for the dental community to participate in what could be a groundbreaking research project."

Wenig and members of his team recently returned from southern California, where they met with UCLA colleagues, who are working to develop saliva diagnostic tests for other cancers as well.

"These tests are as noninvasive as it gets; patients simply need to spit into a cup," Wenig said. "The ease of the test will greatly expand our ability to effectively screen for the cancerous lesions.

"Right now, there are no early screenings available for most head and neck cancers."

The test also has the potential to accelerate health care savings, he added, since the number of biopsies can be dramatically reduced.

TEETH WHITENING ADS  REALLY WORK ????

Many people buy so-called "Teeth Whitening" toothpaste hoping to get whiter teeth. For many people, these toothpastes do not provide whiter teeth. Is this a form of false advertising? Actually, it's not.

The confusion lies in the definition of teeth whitening. Teeth whitening in its strictest sense means to whiten the teeth to their natural shade. Teeth bleaching, on the other hand means to whiten your teethbeyond their natural shade.

The reason there is so much confusion is because the phrase teeth bleaching isn't very attractive. So, companies that offer teeth bleaching, have started to refer to it as teeth whitening to make it more attractive to the average consumer.

In order for a toothpaste, mouthwash, or gum to be certified by the ADA as tooth whitening, it simply has to be able to remove surface stains off of your teeth.

How Teeth Get Stained
When our permanent teeth come in, they are a shiny white color. However, as we grow older (and eat lots of teeth-staining foods), our teeth get more and more yellowish-brown. Teeth Whitening toothpaste can remove tobacco stains, coffee stains, and other stains that we get as we go through our everyday lives.

Unfortunately, tooth whitening toothpastes can only return our teeth back to their original color. The toothpaste contains very gentle abrasives that rub against the stain and gradually remove it.

Why Teeth Whitening Toothpaste May Not Whiten Your Teeth
If you don't drink coffee much or chew tobacco, there's a good chance that your teeth aren't stained at all. In this case, if you use tooth whitening toothpaste, you probably won't notice a difference in how white your teeth are.

Also, in the last ten years, it seems that all toothpastes are "teeth whitening". Chance are, you've already been brushing with "tooth whitening" toothpaste. Continuing to brush with "tooth whitening" toothpaste isn't going to make your teeth any whiter since you've already removed the stains with previous tubes of "teeth whitening" toothpaste.

How to Whiten Your Teeth
If you truly want whiter teeth, you will probably want to use a form of teeth bleaching. Teeth bleaching is designed to whiten your teeth beyond their natural shade.

You should talk to your dentist about teeth whitening options such as in-office gels, Zoom teeth whitening, and take-home teeth whitening gels.

A Drug used to Treat Osteoporosis may Help Reverse Inflammatory Gums and Teeth



In a post on intelihealth.com, the News ReviewFrom Harvard Medical School has released an article stating that a drug call teriparatide (Forteo) may actually help bone repair for those suffering from periodontitis.

What is periodontitis? Well, most of us know its precursor, gingivitis. Gingivitis symptoms include red, swollen gums that bleed easily.

Periodontitis is when the gum disease has been left untreated as gingivitis and has become more severe. Periodontitis can lead to bone loss under teeth as well as teeth themselves. Symptoms of periodontitis include pus between teeth and gums, gums pulling away from teeth and permanent teeth that are becoming loose.

Teriparatide is currently used to help build bone in people suffering from osteoporosis. According to intelihealth.com, “It [teriparatide] actually stimulates new bone formation. But doctors also know that this drug, if given for more than two years, might increase the risk of developing bone tumors.” Thus, it is not the most commonly prescribed drug to help with osteoporosis.

However, in terms of people with periodontitis, teriparatide might really help, as it “did seem to help stimulate bone growth in the mouth.”

There are plans for more testing with periodontitis suffers. As intelihealth.com states, “We clearly need larger studies of this drug in the treatment of periodontitis. I think we also will see trials of this drug in the treatment of osteonecrosis of the jaw and of other areas of bone.”

While there may be a new treatment for periodontitis on the horizon, the best thing you can do is to not let the disease get to this stage. If you notice that your gums are red or bleeding, the best thing to do is to maintain a health oral care regimen: brush, floss and rinse at least two times per day. A healthy diet can also aid in beating gingivitis. And make sure you see your dentist regularly. He or she can always offer the best course of treatment for any dental issue.

There are products out there specifically designed to treat your gums and keep them healthy, so that may be something worth trying out. Remember, if you do have gingivitis, it is completely reversible. Just put the time and love into taking care of your mouth — after all, it’s the only one you’ve got.